Ofcourse, the captain is in command of the ship. But who has the bridge during which shift? I would assume that, since we've seen captains in their readyrooms with their first officers on the bridge, that the first officer has the bridge during alpha shift. But what about beta and gamma shift? In some novels, it's been established that ships have command officers, usually in the Lt.Commander rank, who are in command then. Nothing has been clearly stated about beta-shift. Has anything ever been mentioned about this onscreen? And how would it work on an actual navy vessel?